[petsc-users] ASM vs GASM

[Griffith, Boyce Eugene]

I am trying to setup a GASM preconditioner and am running into some difficulty getting convergence even with exact subdomain solvers. I am just doing things in serial now, and tried switching to ASM, and get convergence. I am wondering if I am misunderstanding the GASM interface. If inner_ises and outer_ises define the “inner” and “outer” subdomains for GASM, should GASM and ASM do the same things when configured via:

	PCGASMSetSubdomains(pc, n_subdomains, inner_ises, outer_ises);

and

	PCASMSetLocalSubdomains(pc, n_subdomains, outer_ises, inner_ises);

Thanks!

— Boyce